1. Field of the Invention
The present invention relates to integrated circuit memory generally, and more particularly to integrated circuits with ferroelectric memory cells.
2. Description of Related Art
Ferroelectric memory integrated circuits that store multiple bits per ferroelectric memory cell program the multiple bits by applying different voltage levels to the ferroelectric memory cell. Applying different voltage levels to the ferroelectric memory cell changes the polarization of the ferroelectric material to different degrees. However, if the voltage level applied to the ferroelectric memory cell is the only input variable which determines the states of the multiple bits stored in the ferroelectric memory cell, the design of the control circuitry is constrained. For example, a particular memory application may be less suited to programming the ferroelectric memory cell, or a particular memory application may not require that a ferroelectric memory cell must be programmed in the same amount of time, regardless of the values of the multiple bits that are programmed into the ferroelectric memory cell. Accordingly, what is needed are alternatives to programming different multiple bit in a ferroelectric memory cell other than varying only the voltage level applied to the ferroelectric memory cell.